College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, PR China.
College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, PR China.
Sci Total Environ. 2017 Dec 1;599-600:207-216. doi: 10.1016/j.scitotenv.2017.04.235. Epub 2017 May 3.
Biochar samples produced from rice straw by pyrolysis at different temperatures (400°C and 800°C) and under different atmospheres (N and CO) were applied to lettuce growth in a 'preparation-application' system. The conversion of potassium in the prepared biochar and the effect of the temperature used for pyrolysis on the bioavailability of potassium in the biochar were investigated. Root samples from lettuce plants grown with and without application of biochar were assayed by X-ray photoelectron spectroscopy (XPS). The optimal conditions for preparation of biochar to achieve the maximum bioavailability of potassium (i.e. for returning biochar to soil) were thus determined. Complex-K, a stable speciation of potassium in rice straw, was transformed into potassium sulfate, potassium nitrate, potassium nitrite, and potassium chloride after oxygen-limited pyrolysis. The aforementioned ionic-state potassium species can be directly absorbed and used by plants. Decomposition of the stable speciation of potassium during the pyrolysis process was more effective at higher temperature, whereas the pyrolysis atmosphere (CO and N) had little effect on the quality of the biochar. Based on the potassium speciation in the biochar, the preparation cost, and the plant growth and rigor after the application of returning biochar to soil, 400°C and CO atmosphere were the most appropriate conditions for preparation of biochar.
由不同温度（400°C 和 800°C）和不同气氛（N 和 CO）下热解稻秆生成的生物炭样本被应用于生菜生长的“准备-应用”系统。研究了制备生物炭中钾的转化以及热解温度对生物炭中钾生物有效性的影响。通过 X 射线光电子能谱（XPS）分析了施加和不施加生物炭的生菜根系样本。因此，确定了制备生物炭以实现钾最大生物有效性（即将生物炭返回土壤）的最佳条件。在有限氧的热解作用下，稻秆中稳定的钾络合物复杂-K 转化为硫酸钾、硝酸钾、亚硝酸钾和氯化钾。上述离子态钾可被植物直接吸收利用。在较高温度下，稳定的钾络合物在热解过程中的分解更有效，而热解气氛（CO 和 N）对生物炭的质量几乎没有影响。基于生物炭中钾的形态、制备成本以及施加生物炭返回土壤后的植物生长和活力，400°C 和 CO 气氛是制备生物炭的最适宜条件。
